The United States says U.S. diplomats are looking into reports of vote fraud in Sunday's election in Cambodia but the State Department says the election process overall appears to have been carried out in an "orderly" way.

The Bush administration and key members of Congress have been critical of the Cambodian government of Prime Minister Hun Sen and its conduct of past elections.

But the initial U.S. reading on Sunday's national assembly polling is that it was carried out in a "generally orderly fashion," after a campaign that featured fewer incidents of violence than in the previous elections in 1998 and 2000.

At a briefing here, State Department spokesman Richard Boucher said it was too soon to give an overall judgment but said that the election mechanics went smoothly, and that the ballot count must now be conducted in accordance with the country's election law and be fully monitored.

He said the U.S. embassy in Phnom Penh is following up on reports of some election irregularities including faulty voting rosters and charges of vote buying and intimidation, and said Cambodian authorities have a responsibility to act on them.

"The National Election Committee must investigate allegations of irregularities expeditiously, correct any problems found, and punish any transgressors," he said. "So, by and large, things went smoothly. The overall conduct of the elections was marked by less violence and more access to the media than in previous times, but there were some election irregularities reported and we would expect those to be looked into and followed up by the National Election Commission."

Mr. Boucher also said voter turnout appeared Sunday to have been lower than previous elections.

Final results from the election are not due for more than a week, but unofficial returns gave Mr. Hun Sen's party a broad lead over its rivals, who immediately disputed the outcome.

It appeared however that the ruling Cambodian People's Party would not win a two-thirds majority in the assembly needed to govern and would need to form a coalition.